Clothing, wine choices, ways of speaking, and other behavioral and sartorial signs are metaphors for social class and level of education.
Overall, education is a metaphor for being civilized, for being cultured, for being of a higher social strata. It is not representative of merely writing essays or knowing who the best poets are.
Rita's cutting of Frank's hair may be a metaphor for her pruning away the things that are holding him back, and allowing him to go off to Australia and discover a new life for himself, full of renewed purpose and drive. This, of course, is speculative, because it is outside the span of time covered by the play.
"I'm as fucked as a fanny on a Friday night!" -Rita, 8
Educating Rita Questions and Answers
The Question and Answer section for Educating Rita is a great
resource to ask questions, find answers, and discuss the novel.